1. Field of the Invention
The present invention generally relates to a motor and, more particularly, to a motor that separates its coil unit from a metallic casing thereof for insulation purposes.
2. Description of the Related Art
Referring to FIG. 1, Taiwanese Patent Publication Number 201032444 discloses an inner-rotor-type motor 7 including a casing 71, a stator 72 and a rotor 73. The casing 71 is hollow and is used to receive the stator 72. The stator 72 consists of a plurality of silicon steel plates 721 and a coil 722. The rotor 73 is rotatably coupled with the casing 71. Based on this arrangement, the rotor 73 can be coupled with an impeller 74 so that the impeller 74 may provide a cooling effect when the stator 72 drives the rotor 73 to rotate.
The casing 71 of the inner-rotor-type motor 7 is usually made of metal material. Since there is no insulation between the coil 722 of the stator 72 and the casing 71, the coil 722 could be short-circuited with the casing 71 once the enamel coated on the coil 722 comes off. Thus, operation of the inner-rotor-type motor 7 is impacted.
In light of the problem, referring to FIG. 2, Taiwanese Patent Publication Number 201031087 discloses an inner-rotor-type motor 8. The inner-rotor-type motor 8 includes a casing 81, a stator 82 and a rotor 83. The casing 81 is hollow and is used to receive the stator 82. The stator 82 consists of a plurality of silicon steel plates 821, an upper insulation bobbin 822, a lower insulation bobbin 823 and a coil 824. The rotor 83 is rotatably coupled with the casing 81.
In the above inner-rotor-type motor 8, the silicon steel plates 821 are stacked with each other to form a silicon steel plate unit. Then, the upper insulation bobbin 822 and the lower insulation bobbin 823 are coupled with two ends of the silicon steel plate unit, respectively. Finally, an enameled wire is wound around predetermined portions of the silicon steel plate unit, upper insulation bobbin 822 and lower insulation bobbin 823 to form the coil 824. Based on this, once the enamel coated on the coil 824 comes off during the winding process, the upper insulation bobbin 822 and lower insulation bobbin 823 may provide an insulation effect therefor.
However, referring to FIG. 3, a conventional stator 9 is shown. The conventional stator 9 includes at least one insulation bobbin 91 which generally has a plurality of connection portions 92. During the winding process of windings 93, the connection portions 92 may connect all windings 93 together. When the conventional stator 9 is received in a metallic casing of a motor and although the insulation bobbin 91 is able to keep certain portions of the windings 93 away from the metallic casing, insulation for the portions of the windings 93 that are wound around the connection portions 92 is not provided. Furthermore, the windings 93 of the conventional stator are generally connected to a circuit board. In this case, improper contact between the metallic casing and the portions of the windings 93 that are connected to the circuit board, or between the casing and wires of the circuit board, can easily occur. Therefore, when the conventional stator 9 having the at least one insulation bobbin 91 is received in a metallic casing of a motor, improper contact between the metallic casing and the windings 93, or between the metallic casing and the wires of the circuit board, is possible, causing short circuit of the windings 93 or the wires of the circuit board. As a result, operation of the motor is impacted.